WHAT THE NOSE KNOWS

The Science of Scent in Everyday Life

A scientist tells us entertaining things about odors both pleasant and foul.

Olfactory researcher and psychologist Gilbert asks a dozen questions in no particular order and then answers them—often with “we don’t know,” but always with enthusiasm and wit. How many smells are there? About 10,000, declared two scientists who won the Nobel Prize for smell research, a figure regularly quoted by other experts. Tracking down this conveniently round number, Gilbert discovers that scientists are quoting from earlier scientists, who found it in a still older scientific paper that cites an even earlier researcher, who seems to have picked the number out of his hat. Scientists today can analyze a tiny sample of a chemical, perfume, food aroma or flatulence and obtain a precise molecular breakdown of every ingredient. Does that mean they can design a new scent by manipulating atoms, the same way medical scientists design new antibiotics? Not yet, the author admits. He disagrees with biologists who claim evolution has withered smell into the least important human sense; actually, he maintains, evolution is expanding our capabilities in this area, and smell is as essential as vision or hearing. Research shows that we detect smells as acutely as monkeys and apes and don’t do badly compared with more distant relatives. Nose to the ground, humans can follow a scent trail. Along with tool use and a large brain, cooking is one of the traits that separate modern humans from their ancestors. Not only does it make food easier to digest, but the spectacular complexity of food preparation and our intense preoccupation with flavors (in which smell plays a far greater role than taste) are uniquely human attributes.